Hello all and thank you for your help.

I have two 2001 1.4 mpi fabia and one 2003 mpi fabia.

I bought an immobilizer kit from the scrapyard (key, ignition lock with coil, ECU and instrument cluster) from other 1.4 MPI.

It works with no problems in the 2001 cars but in the 2003 car the security dash light (car with key) keeps blinking and car runs for 2 seconds and shut down.

The ECU part is the same with only one difference. In the 2001 cars ends with C and in the 2003 car ends with H. Kit ends with C.

Engine, gearbox, central electronic, instrument panel, etc is the same in all three and with the car of the kit. Version AQW.

My question is:

It is a matter of wiring and pinout? i Have the 2003 electric schematics but not the 2001. Someone has it?

ChatGPT tells me that the 2001 Fabias worked with K-line and 2003 with CAN. This is reliable?

Thank you

Think they worked with both. Some systems can-bus and rest K line. The symptoms are definitly imobilser linked. Wonder if the newer uses more Can-bus or perhaps something else that requires coding to ECU. Not sure but maybe BCM although don.t think its imobilser linked but may be linked to cluster.

Alasdair

Thank you for your answer. The cluster is part of the kit also. I replaced all pieces. I already found the 2001 schematics and I am going to compare pinout and wiring with the 2003. There is something I noticed today. The 2003 car has no anti theft alarm and the two from 2001 have it.

That's odd I thought they all had anti theft alarm unless someone has removed it. I had a quick google and 2001 I think uses Immo2 which is simpler. 2003 I think uses Immo3 which is more complicated. At this point I am now lost as its above my learning curve. I would assume by swapping all relevant modules etc it would work. It must be an imobiliser problem or incompatabilty somewhere.

Alasdair

Mine has no alarm, from factory. It's never gone wrong. 😁

SOLVED. Cheap AliExpress radio messing with k-line. Chatgpt told me to check that has usual fault. Thank you all.

That was on my mind to ask next. Glad you got it sorted. Its amazing how a radio can affect them. Last one I read was no OBD2 connection/communication

Alasdair

On 07/04/2026 at 17:01, Breezy_Pete said:

Mine has no alarm, from factory. It's never gone wrong. 😁

Same here (2006 Ambiente, middle trim model). I believe it was standard equipment on the Elegance but optional on the rest.

Thats odd as my sons 55 plate 1.2htp has one and also my folks old 1.9tdi estate 56 plate had one that got disabled as it kept going off randomly. Both were mid range not elegance models. Maybe it was an extra spec when ordering from new.

Alasdair